1. Field of Invention
This invention relates to a manufacturing machine for producing cigarettes composed of tobacco portions having different characteristics.
2. Description of Related Art
It is well known that the use of a single tobacco mixture for producing cigarettes can lead to certain drawbacks in that, for example, in a cigarette that tobacco portion furthest from the lit end behaves as a filter during cigarette combustion, and retains the combustion products to give the final part of the cigarette a taste which gradually differs from that of the initial part.
In order to adjust the aforesaid characteristics at will, it has been proposed to manufacture cigarettes using several tobacco mixtures located in different cigarette zones so that the said characteristics become influenced in a required and determined manner during the cigarette combustion time.
To obtain cigarettes of this type, manufacturing machines have been proposed in which two ascending shafts disposed one following the other successively feed a suction belt conveyor with two continuous layers of tobacco of different type. At the outlet of the first shaft, a trimmer device removes equidistant tobacco portions from the first layer to create spaces which are then filled with tobacco of the second type by the second shaft.
A second trimmer device disposed downstream of the second shaft along the path of said conveyor makes the thickness of the overall tobacco layer obtained uniform.
A drawback of manufacturing machines of this type is that the two said trimmer devices trim away a large quantity of tobacco, which is known to result in considerable quality loss.
A further drawback of such manufacturing machines is their considerable structural complexity due to the presence of the two shafts and the two trimmer devices, and their considerable overall size due to the presence of the two said consecutive ascending shafts.